1. Field of the Invention
The present invention relates to a cigarette, and more particularly, to a cigarette extinguishable unless smoked for a certain period of time after ignition.
2. Description of the Related Art
It is widely known that a cigar exhibits a so-called self-extinguishing phenomenon that the burning portion is extinguished, unless the cigar is smoked for a certain period of time. Although there are various opinions concerning the causes of the self-extinguishing phenomenon, it is clearly one of the causes of the self-extinguishing phenomenon that the wrapper (tobacco leaves or a sheet prepared by processing tobacco leaves) of the cigar covering the shredded tobacco is unlikely to be burned. On the other hand, it has also been attempted to manufacture a self-extinguishing cigarette by using a wrapping paper sheet that is unlikely to be burned. Concerning the particular wrapping paper sheet, a wrapping paper sheet mixed with a metal is proposed in, for example, Japanese Patent Disclosure (Kokai) No. 55-29955, and a wrapping paper sheet mixed with sepiolite is proposed in Japanese Patent Disclosure No. 59-21800. Also, disclosed in Japanese Patent Disclosure No. 60-164472 is a self-extinguishing cigarette, in which an inflammable material such as an aluminum foil is formed annular around a wrapping paper sheet such that the burning of the cigarette is stopped at the annular inflammable material if the cigarette is not smoked for a certain period of time.
The conventional design technology of the self-extinguishing smoking article can be said to be satisfactory when it comes to only the aspect of providing merely a self-extinguishing cigarette. However, the smoker feels very inconvenience, if the ignition is poor in smoking, for example, a cigar. Also, the pleasant smoking time is spoiled if the cigar is extinguished during the smoking. Such a problem also takes place in the conventional self-extinguishing cigarette. The cause of the problem is that, in the conventional cigarette design technology, attention is paid to the self-extinguishing properties alone, and the general smoking behavior of the smoker is neglected. In the standard smoking state (ISO), the time between the adjacent puffs (static burn time) is defined to be 58 seconds. However, it is not reasonable to define uniformly the static burn time because smoking is a pleasure enjoyed by the individual smoker, though a cigarette that continues the static burn for a long time is not desirable in view of fire prevention.
Accordingly, an object of the present invention is to provide a self-extinguishing cigarette, in which the static burn time is assumed to be about 2 to 4 minutes, which is far beyond the static burn time in the ordinary smoking behavior, so as to permit the cigarette to be self-extinguished if the static burn of the cigarette is continued for at least 2 minutes.